Theftproof lamp



June 20, 1933. J. P. PETH 1,914,702

- THEFTPROOF LAMP Filed March 28, '1951 fa/Zn PPeZk Patented June 20, 1933 UNITED STATES JOHN P. PETH, OF CHICAGO, ILLINOIS THEFTPROOF LAMP Application filed March 28, 1931'.

, My invention relates to a theft-proof electric lamp and more particularly to a theftproof lamp which will be rendered useless if removed from a lamp socket to which it has once been applied.

The invention is an improvement of the theft-proof lamp shown in my prior Patent #1,556,342, issued October 6, 1925, disclosing an electric lamp in which the bulb must be broken in order to remove the lamp from a socket after it has been inserted therein. This is a common feature of theft-proof lamps now on the market. The breaking of the bulb, however, subjects the user to the hazard of being injured by the shattered glass and also of receiving a shock by coming in contact with the filament support wires in the bulb.

In accordance with'the general features of the present invention I provide a lamp which may be removed from the lamp socket but which will be as useless after removal as if the bulb had been broken.

An object of the invention is to provide a new and improved theft-proof lamp.

A further object is to provide a theft-proof lamp which may be removed after it is burned out without breaking the bulb.

A further object is to provide a lamp which will be rendered useless if removed from a socket in which it has once been inserted.

A further object is to provide a lamp in which the circuit to the filament will be broken by removing the lamp from the socket.

Other objects and advantages will appear as the description proceeds.

Referring to the drawing,

Fig. 1 is a fragmentary sectional view of an electric lamp embodying my invention,

Fig. 2 is a sectional plan view taken on line 2-2 of Fig. 1,

Fig. 8 is a detail view of the base of the lamp with the outer shell removed,

45 Fig. 4 is a sectional detail view ta-l'ren on line 44 of Fig. 3,

Fig. 5 is a fragmentary sectional view of a modification of the device shown in Fig. 1,

Fig. 6 is a fragmentary sectional view of a modified form of the invention having a base of vitreous material, and

Serial No. 525,903.

Fig. 7 is a fragmentary elevation ofthe base shown in F 6'looking' at F ig. 6 from the right.

Referring now more in detail to the drawing, the lamp comprises a bulb 11 mounted upon a base which consists of a cylinder 12 having a cylindrical block 13 of any suitable insulating material in* the upper end thereof. The upper end of cylinder 12"has an inturned flange 14 to prevent thewithdrawal of the 69 block from the shell. The lower end of cylinder 12 is provided with a circumferentialbead 15. Surrounding the base formed by cylinder 12 and block 13 is a threaded screw shell 16, which is adapted to be inserted in a cooperating screw shell of a socket for the lamp. The upper end of screw shell 16 has an inturned flange 17 overlying the flange 14 of the base and the lower end of the screw shell has an inturned flange 18 engaging under the bead 15 so as to prevent axial move ment of the screw shell on the base, but permitting free rotation of the screw shell on the'base. It is evident that in order to insert V the lamp in a lamp socket, the screw shell must be held against rotational movement relative to the base, while the lamp is being inserted. To this end a depression 19 is formed in block '13- and a similar depression is formed in the cylinder overlying the de- 86 pression 19. In orderto interlock the screw shell and base, a small portion of the'meta'lof the screw shell is forced into the depression in the base by means ofv apoi'nted tool. .7 When the lamp is turned into a socket, the screw shell 16 turns with the lamp until the base of the lamp strikes the end of the socket. An additional turn of the lamp will then bend the material of screw shell 16 out of the depression in the base, and since the screw 90 shell is made of relatively soft material having a low degree of resiliency, the disconnection of the shell and base will be permanent. The lamp may now be freely rotated in either direction without unscrewing it from the socket. After the filament of the lamp is burned out, the lamp must of course be removed from the socket and in order to obviate the shattering of the glass of the bulb to v remove the lamp from the socket, I provide 109 means for re-establishing a connection between the base and screw shell so that the lamp may be readily removed. This means consists of a detent 21 placed in a radially extending aperture in the base and a spring 22 yieldingly urges the detent outwardly. The end of the detent is reduced as shown at 23 and the cylinder 12 is provided with an aperture in alignment with the detent. This detent is normally held depressed by a pin 24. Cylinder 12 is provided with a plurality of circumferential slots 25 which form a plurality of strips 26, 27 and 28. The strip 27 is allowed to remain as shaped, but strips 26 and 28 are bent inwardly at a sharp radius to provide a bearing and guide for pin 24. When the pin is in its uppermost position it overlies the end of detent 23 and holds the detent in depressed position. However, by pulling the pin downwardly the detent is released and is pushed outwardly by spring 22 against the inner periphery of screw shell 16. v The screw shell is provided with an aperture 31 in axial alignment with the detent so that upon rotation of the lamp and base the detent will enter aperture 31 when it comes in angular alignment with the aperture, thereby interlocking the baseand screw shell 16. Thus, the lamp may be removed from the socket withoutdestroying the bulb. However, it is intended that the lamp should be removed from the socket only after it is burned out. If it is attempted to remove the lamp from the socket before it is burned out, I provide means for breaking the filament circuit of the lamp so as to render the lamp useless and inoperative when the pin is pulled downwardly to release the detent. The lamp is provided with the usual press or stem 32 through which lead wires 33 and 34 are sealed into the bulb for supporting and making contact with the filament of the bulb. Lead 33 goes directly to a center contact 35 on the bottom of the base in the usual manner. Lead 34, however, passes over the upper end of the bulb and downwardly to a point 36 where it is soldered to pin 24. This lead may have a kink in it as shown, so that it will break readily at this point. The pin being inelectrical contact with the screw shell 16, this interconnects lead 34 to the screw shell. If now the pin 24 is pulled downwardly to release the detent, the wire soldered connection to the pin at point 36 will be broken to interru t the filament circuit of the lamp, or the lead will break at the kink.

An alternative way of interrupting the fil ment circuit of the lamp is shown in Fig. 5 in which a filament lead 34' is shown soldered to' pin 24 at a point 38 just above the strip 28. It will be seen that when pin 24 is pulled downwardly, the wire. soldered connection at point 38 will be sheared from the pinbyta strip 28 to sever the connection be tween the filament lead and the pin.

In Figs. 6 and 7 I have shown the invention applied to a porcelain base 41 in most respects similar to the base of the device shown in Fig. 1. The screw shell is interlocked with the base by depressing a small portion of the shell into a depression 19 and the connection is re-cstablished between the screw shell and the base by a. detent 23". The chief difference in this modification lies in the 1nanner of supporting the pin 24 in the base. in order to support this pin in the base, the base is provided with a longitudinal slot 39 of such depth that when the pin 24 lies in the groove its outer side will Contact with the screw shell to make electrical contact therewith. l ithin the groove the base is provided with an aperture 41 and filament lead 34 is soldered to pin 24 through this aperture. The aperture is provided with rectangular edges so that when the pin is pulled downwardly the soldered connection will be sheared from the pin.

The invention provides a convenient and eli'ective means for removing a theft-proof lamp from a socket after it is burned out without breaking the glass of the bulb and at the same time it removes all incentive to stealing the lamps, because the removal of the lamp destroys the filament circuit of the lamp and rent ers the lamp useless. It is not essential th at the it'eatures of the invention be used. in the exact combinations shown. The fea tures of one embodiment may be used with features of the other embodiments as desired.

It will be understood that the nature and embodiment of the invention herein described and illustrated are merely convenient and useful forms of the invention, and many changes and modifications may be made therein without departing from the spirit and scope ot the invention.

What I claim as new and desire to protect by Letters Patent of the United States is 1. In a theft-proof electric lamp, :1. base for supporting the bulb of the lamp, a shell surroundingsaid base, a spring pressed detent carried by the base and adapted to engage the shel and a stop member carried by the shell and adapted. to be withdrawn to permit the detentto en!" the shell.

2. In a theft-proof electric lamp, a base for supporting a bulb, a shell surrounding the base, an easily disrupted connection between the base and shell whereby the shell may be screwed into a socket and then separated from the base by rotating the base to break said connection and permit the base to be rotated in either direction with respect to the shell, a spring-messed detent carried by the base and adapted to engage the shell, a stop member normally engaging said detent to prevent i from engaging the shell, and means for withdrawing said stop member.

3. A theft-proof electric lamp as defined in claim 2, wherein said stop member forms part of the electrical contact between the shell and filament of the lamp whereby removal of said stop member will render the lamp inoperative.

4. In a theft-proof electric lamp, a base for supporting the bulb, a shell surrounding the base, the shell forming one of the usual contacts with a socket, an easily disrupted connection between the base and shell whereby the shell may be inserted in a socket and the base then separated from the shell to permit rotational movement between the shell and base, a spring pressed detent carried by the base and adapted to engage the shell to interconnect the shell and base, a removable stop member for preventing the detent from engaging the shell, and a lead-in wire connected to the stop member and adapted to bev broken when said stop member is removed to re-establish connection between the shell and base.

5. In a theft-proof electric lamp, a base, a bulb secured to the base and having the usual filament, lead-in wires connected to the filament, a shell surrounding the base, and rotatable with respect thereto, a spring pressed plunger readily disposed in the base and adopted to engage an aperture in the shell, a pin carried by the base and serving as a stop to prevent the plunger from engaging the shell, one of the lead-in wires being secured to said pin and the pin in communication with the shell, and means for withdrawing the pin.

6. A theft-proof electric lamp as defined in claim 5, including a readily disrupted connection between the shell and base, said connection adapted to be broken when the shell is screwed into the socket.

7. In a theft proof electric lamp having the usual filament and lead wires for supplying current to the filament, a base for supporting the bulb of the lamp, a shell rotatably mounted on said base, a disruptable connection between said shell and base comprising corresponding indentations in said shell and base whereby when the lamp is screwed into position said connection is broken and the lamp may turn free of the shell, means including a vertically slidable pin for re-connecting said shell and base, and means including said pin for breaking one of the lead wires to render the lamp inoperative.

8. In a theft-proof electric lamp, a base for supporting the bulb of the lamp, a shell surrounding said base and rotatable relative to said base, a disconnectible connection between said shell and base whereby when the lamp is screwed into position said connection is broken and the lamp may be turned in either direction free of the shell, means for re-establishing a connection between said shell and base including a movable detent carried in said base, and means including a vertically slidable pin for releasing said detent to interlock the shell and base.

9. In a theft-proof electric lamp for insertion in a socket, a base for supporting the bulb of the lamp comprising a cylinder having an insulating block secured therein, a shell rotatably mounted on said base, a depression in said block and a corresponding depression in said cylinder, a disruptable connection between said shell and base comprising an indentation in said shell adapted to fit into the depression in said cylinder, whereby when the lamp is screwed into position said connection is broken and the lamp and base may be turned in either direction free of the shell, and means for reconnecting said shell and base including a movable detent and a slidable pin, whereby said lamp may be removed from the socket.

In witness whereof, I hereunto subscribe my name this 21st day of February, 1931.

JOHN P. PETH. 

